The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Most aircraft include landing gear whose essential functions consist, on the one hand, in absorbing a large part of the kinetic energy due to the vertical component of the speed of the aircraft on landing, and, on the other hand, in allowing the aircraft to move on the ground, in particular during the braking phase.
The aircraft braking systems include braking actuators (hydraulic or electromechanical), controlled to apply a braking torque to the wheels of the aircraft aiming to slow it down.
The control of the braking systems generally includes brake assist systems, such as for example an anti-skid system or an automatic braking system (usually called “autobrake” system).
The anti-skid system, or anti-slip protection, allows automatically regulating the braking force applied to each of the braked wheels, in order to prevent any blocking or skid of any of the wheels. To this end, each braked wheel is equipped with a rotation speed sensor, the data measured by these sensors allow detecting the slip of one or more wheel(s).
The automatic braking system allows automatically obtaining the deceleration of the aircraft, the necessary braking force being calculated and controlled by the system, in particular depending on a preselected stopping distance by the pilot. When the automatic braking system is activated, it is no longer necessary that the pilot monitors the braking via the brake pedals (or rudder pedals).
When an aircraft is driven by turbojet engines, a part or all of these turbojet engines are generally equipped with a thrust reverser system. The role of a thrust reverser is, during landing, to improve the braking capability of the aircraft by redirecting forwards at least one part of the thrust generated by the turbojet engine. In this phase, the thrust reverser directs forwardly at least one portion of the ejection flow of the turbojet engine, thereby generating a counter-thrust which is added to the braking of the wheels and the airbrakes of the aircraft.
In the case of bypass turbojet engines, which generate both a hot gas flow (main flow) and a cold air flow (secondary flow), a thrust reverser might act on the two flows, or act only on the cold flow.
In general, the thrust reversers are equipment which undergoes very high mechanical stresses and which must meet strict specifications, in particular in terms of reliability of operation. This equipment is therefore designed accordingly, which negatively impacts the mass and the cost of the propulsion system.
Moreover, when the thrust reverser system of a turbojet engine is activated, the resulting counter-thrust will be more significant as the motor speed will be high. The use of a thrust reverser therefore generally occurs at a high motor speed, for example about 75% of the maximum speed. In some cases, such as for example an emergency landing or an aborted take-off, the motor speed may be even higher. This has the direct consequence of a significant load on the motor, which impacts its service life.